Impacts of blue-green infrastructures on combined sewer overflows

In recent years, there has been a growing focus on combined sewer overflows (CSOs), due to the attention posed by laws and regulations on environmental protection. Urbanization and climate change increase the activation of CSO both in terms of frequency and volume of uncontrolled polluted discharge into receiving water bodies. Blue-Green Infrastructures (BGI) are more and more encouraged as strategies and solutions for runoff control and stormwater management, providing several benefits to the environment and communities. This manuscript aims to serve as a review paper of the impacts of BGI on CSOs from a quantitative and qualitative point of view, with a focus on the challenges posed by climate change and innovative modelling based on real-time control (RTC) and artificial intelligence (AI). The research highlighted the advantages of each BGI and emphasized that their combination can improve the benefits of runoff control and environmental protection. This study can be useful to planners and engineers to guide the selection and implementation of BGI to safeguard water bodies from CSO-related pollution.